Silicic Acid (Hetero) Polycondensates Comprising Organically Polymerisable Groups and Either Sulphonate Groups or Sulphate Groups, Organic Polymerisates Produced therefrom, and a Method for Producing said Polycondensates

ABSTRACT

The invention relates to silicic acid (hetero) polycondensates consisting of at least one silane that has a group bonded to silicon by a carbon atom and that carries an organically polymerisable C═C double bond, and at least one silane that has a group bonded to silicon by a carbon atom and that carries a sulphonate group or a sulphate group of the formula —(O) d -SO 3 M wherein d=0 or 1 and M=hydrogen, or a monovalent metal cation, or the corresponding quantity of a polyvalent metal cation, yet not including polycondensates in which the C═C double bonds are formed exclusively by methacrylic esters that are bound, in the form of a methylene acryl ester group, to the groups bonded to silicon by carbon. The invention also relates to composites that consist of such silicic acid (hetero) polycondensates in combination with fillers, and to polymers produced by organically polymerising the C═C double bonds in the polycondensates or composites. Moreover, the invention relates to different possibilities for producing the claimed silicic acid (hetero) polycondensates.

Silicic acid (hetero) polycondensates comprising organicallypolymerisable groups and either sulphonate groups or sulphate groups,organic polymerisates produced therefrom, and a method for producingsaid polycondensates

The present invention concerns silicic acid (hetero) polycondensates,comprising first groups, bonded by carbon to silicon and comprising atleast one polymerizable C═C double bond, as well as second groups, alsobonded by carbon to silicon and comprising either sulfonate or sulfategroups, as well as polymers which can be obtained by the polymerizationof the afore mentioned double bonds.

Polymerizable organic compounds with acid groups are importantcomponents for medical products for achieving desired materialproperties like wetting, etching effect, complexing, and therebyadhesion on biological interfaces. Dental adhesives are based on suchconventional monomeric compounds, but exhibit still some considerabledeficits. An essential problem in this context is that the etchingeffect is often insufficient within the context of self-etch applicationfor realizing the necessary retentive structures required for theadhesion and thus a long-lasting connection between dental tissue andrestoration material. Therefore, a prior separate etching step with anetching gel cannot be avoided; this, in turn, increases thesusceptibility for errors and the treatment costs. Concerning theincreasing demands in regard to biocompatibility (reference is being hadto the allergy discussion in connection with dental monomers), the abovesystems also offer no solution. Since the components of the adhesive incase of a restoration come closest to the tooth roots as well as bloodvessels, it is of special interest from a toxicological viewpoint toprovide systems that are free of monomers.

In the patent application DE 44 16 857 C1, carboxylicacid-functionalized (meth)acrylate alkoxysilanes are described. They arecharacterized by a plurality of possibilities for varying or adjustingthe properties of the inorganic-organic composite polymers producedtherefrom. As a result of the contained carboxylic acid groups,additional reaction possibilities (e.g., glass ionomer reactions) aswell as an improved adhesion on inorganic surfaces arise. The etchingeffect (see self-etch application) of a carboxylic acid group is howevernowhere as strong as that of an S—OH functionality. The same holds truefor the phosphonic acid-based systems disclosed in EP 1 377 628 B1.Therefore, up to now, it is not possible to obtain with hybridpolymer-based systems a stable enough connection between dental tissueand restoration material in the context of the desirable self-etchapplication.

For several application purposes, like the stabilization of aqueoussilicates or the production of electro-viscous liquids, emulsifiers,detergents or foaming agents, monomeric or condensed silanes containingsulfonate or sulfate groups have been developed. Thus, U.S. Pat. No.6,777,521 discloses silicone sulfate polymers which are obtainable bythe reaction of suitable epoxy compounds with metal sulfate. U.S. Pat.No. 3,328,449 discloses sulfopropylated organo-functional silanes andsiloxanes which can be obtained by means of reacting sultones. Organosiloxane sulfosuccinates in which a sulfonated succinic acid ester isbonded by the oxygen atom of the ester group by an alkylene group to asilicon atom are disclosed in U.S. Pat. No. 4,777,277. The preparationof a hydrolytically condensable bis-sulfosuccinate amide of adiaminosilane, obtained by the reaction of the free carboxylic acid ofthe suitable succinate amide with sodium sulfite, is disclosed inexample 1 of U.S. Pat. No. 4,503,242. A silane which carries a sulfonategroup and a hydroxyl group at an alkylene oxyalkylene group of thesilicon is disclosed in U.S. Pat. No. 5,427,706.

The use of purely organic monomers which carry a terminal sulfonategroup as well as an unsaturated olefinic group for concurrent etchingand base-coating (“priming”) of teeth is suggested in US 2002/0119426A1. Also, U.S. Pat. No. 6,759,449 B2 discloses dental adhesivecompositions which carry an organically polymerizable (meth)acrylic acidgroup as well as an acidic group. In this context, no distinction ismade between sulfonate groups and phosphonate groups or other acidicgroups concerning the usability of the compounds and their properties.The same holds true for US 2003/0055124 A1; only for the(meth)acrylamido phosphonic acids, but not for the also disclosedcorresponding sulfonic acids, information is provided for thepreparation. Another application, US 2008/0194730, essentially by thesame group of inventors, suggests again for dental composites the use ofself-etch polymerizable N-substituted (meth)acrylic acid amide monomerswhich carry additionally an acidic unit, selected from phosphonic acidunits and sulfonic acid units. N-methacryloyl aminoalkyl sulfonic acidscan be used according to the disclosure of EP 1 421 927 A1 as self-etchprimers for dental purposes.

DE 102 06 451 A1 discloses dental adhesive compositions from acidicallypolymerizable nanoparts in an aqueous phase. The nanoparticles consistof siloxanes having acidic as well as organically polymerizable groupsbonded thereto. The acidic groups can be either phosphonate groups orsulfonate groups; individual specific advantages for one or the othergroup are not specified. The only example of use discloses a specificadhesion value of a dental adhesive from a phosphonic acid-containingmaterial on a tooth surface. A process for producing sulfonategroup-containing silanes or siloxane is neither mentioned generally norin regard to the disclosed compounds.

There is a need for organically polymerizable silicic acid (hetero)polycondensates of superior properties for the application in particularin the dental field. Here, an improved adhesion and/or an improvedetching function and/or an adaptation of the optical properties for thecosmetic appearance are especially relevant. To provide a remedy in thiscontext is the object of the present invention.

For solving this object, silicic acid (hetero) polycondensates areprovided which have organically polymerizable groups, in particular(meth)acryl groups, as well as sulfate groups or sulfonate groups. Inthis context, it has been surprisingly found that in all preparedmaterials the sulfonate group or sulfate group has a substantiallystronger etching effect than a phosphonate group in a comparableposition.

The silicic acid (hetero) polycondensates according to the inventionencompass first groups, bonded by carbon to silicon and having at leastone polymerizable C═C double bond, as well as second groups that arealso bonded by carbon to silicon and have either sulfonate groups orsulfate groups. These are, at least formally, co-condensates from atleast one silane with a residue, bonded by a carbon atom and carrying anorganically polymerizable C═C double bond, in particular a (meth)acrylresidue, and at least one silane with a residue bonded by a carbon atomand carrying a sulfonate group or sulfate group, in particular of theformula —(O)_(d)—SO₃M with d=0 or 1 and with M=hydrogen or a monovalentmetal cation or the corresponding portion of a multi-valent metalcation. Excluded from the claimed subject matter are such co-condensatein which the C═C double bonds are realized exclusively by (meth)acrylicesters which are bonded in the form of a methylene acrylic ester groupto the groups that are bonded by carbon to silicon because, firstly, theester group of the respective methacrylic esters is not stable withrespect to hydrolysis so that in an undesirable manner free alcoholmolecules can be generated, while at the same time the number ofmethacrylic acid groups possibly may increase uncontrollably, and,secondly, the double bond is less accessible on account of stericconditions because it is not in the outer region of the silyl unit towhich it is bonded so that it cannot be reached as well by its reactionpartners. Moreover, an aspect of the invention concerns a very easyincorporation of the optionally present (meth)acryl groups, which can berealized in that they are reacted in the form of the free acid oractivated acid, i.e., are bonded to the condensates or their silaneprecursors. This has the result that the (meth)acryl groups are presentin the structures incorporated as (meth)acrylic esters, (meth)acrylicamides or (meth)acrylic thioesters.

The expression “co-condensate” is meant to encompass according to theinvention all those condensates which would generate at least twodifferent silanes upon hydrolysis of the Si—O—Si bonds. Supra, they werereferred to “formally” as co-condensates because they can be alsoproduced by hydrolytically condensing a single silane and modifyingafterwards only some of the groups that are bonded by carbon to thesilicon atoms; this will be explained in detail infra.

The organically polymerizable C═C double bond to be employed accordingto the invention is in several embodiments an activated double bond. As“activated C═C double bonds”, groups are to be understood whose doublebonds have in their neighborhood an electron-withdrawing group so thatan attack is possible by a NHR group (a nucleophilic attack).Particularly preferred examples of such residues are acrylates andmethacrylates which, in accordance with the preceding explanations, arein the form of (meth)acryl silyl esters, (meth)acryl silyl amides or(meth)acryl silyl thioesters, i.e., in a form in which the acryl groupis esterified/amidated/thioesterified with the organosilyl group.

Instead of the expression “activated C═C double bonds”, the expression“active C═C double bonds” is also used herein in some places.

As an example of organically polymerizable double bonds that are notactive or not activated, the vinyl group, the allyl group as well asdouble bonds within a ring, such as those in a norbornene group, are tobe mentioned here. These groups are sterically also in an externalregion of the respective silanes so that they are easily polymerized.

The expression “'organically polymerizable” is to be understood as thepossibility of polyaddition of the double bonds, on the one hand, butalso the polymerization by the addition of residues capable of addition,like thio groups or amino groups, on the other hand. Thus, for example,a norbornene group can be subjected to a thiol-ene addition.

The word or the word part **(meth)acrylic . . . ” is meant to encompassthe respective methacryl and acryl compounds alike. The (meth)acrylresidues can be in particular a component of a (meth)acrylic acid ester,thioester or amide. (Meth)acrylic acid amide residues are preferredcompared with the other (meth)acryl residues because of their betterresistance to hydrolysis.

The expression “sulf(on)ate” encompasses the sulfonate group and thesulfate group. The expressions “sulfonate group” and “sulfate group”encompasses the respective acids and salts.

The polycondensates of the invention can be present in many differentembodiments and can be producible according to different variants. Allvariants have in common that they are generated as a rule by the knownsol gel process. In this way, silicic acid polycondensates are producedwhich are often referred to also as ORMOCER®e. The condensation reactioncan occur in the presence of additional silanes of the formulaSiR*_(a)R**_(4-a) which are known in the art in very large numbers. R*means a hydrolyzable group which enables the incorporation bycondensation of the silane into the network, while R** can be anynon-condenseable residue. R* can be herein OH or a C₁-C₁₀ alkoxy group,more preferred a C₁-C₄ alkoxy group, and particularly preferred methoxyor ethoxy. However, R* can be, as needed, also a halide like Cl,hydrogen, acyloxy with preferably 2 to 5 carbon atoms, alkylcarbonylwith preferably 2 to 6 carbon atoms, or alkoxycarbonyl with preferably 2to 6 carbon atoms. In some cases, R* can also be NR² with R² beinghydrogen, alkyl with preferably 1-4 carbon atoms, or aryl withpreferably 6-12 carbon atoms.

In this context, the silanes of both variants are selected in a suitablemanner such that the desired condensation level is achievable with them.Thus, up to three residues, optionally only two residues, of the silylgroup are selected from hydroxyl groups or—preferred—hydrolyzablegroups. Such groups are called generally network formers. Preferably,they are alkoxy groups, aryloxy groups or aralkoxy groups, in particularC₁-C₁₀ alkoxy groups, more preferred C₁-C₄alkoxy groups, andparticularly preferred methoxy or ethoxy. However, as needed in specialcases, it is possible to select be as hydrolytically condenseable groupsin place thereof or partially, in each case independent of each other,halides like Cl, hydrogen, acyloxy with preferably 2 to 5 carbon atoms,alkylcarbonyl with preferably 2 to 6 carbon atoms, or alkoxycarbonylwith preferably 2 to 6 carbon atoms, provided they do not interfere withthe reactions which are needed for producing the condensates accordingto the invention. In individual cases, groups of the meaning NR² with R²being hydrogen, alkyl with preferably 1-4 carbon atoms, or aryl withpreferably 6-12 carbon atoms can be used instead.

In addition, the silanes can also contain groups which are callednetwork modifiers. These are groups which themselves have no influenceon the formation of the condensate but can modify its properties. Theyare preferably alkyl groups, aryl groups, arylalkyl groups, alkylarylgroups or alkylarylalkyl groups that are substituted or unsubstituted,straight-chain, branched or provided with at least one cyclic structure;nevertheless, in individual cases, also corresponding alkenyl groups,arylalkenyl groups or alkenylaryl groups can be present. Preferred arealkyl groups, aryl groups or aralkyl groups, in particular C₁-C₁₀ alkylgroups, more preferred C₁-C₄ alkyl groups, and particularly preferredmethyl or ethyl.

In exceptional cases, a single silane can have two groups that arebonded by carbon to the silicon which either both have at least onepolymerizable C═C double bond or both have a sulfonate group or sulfategroup.

When three hydrolyzable groups/hydroxyl groups are present, athree-dimensional network is generated while silanes with two hydroxylgroups/two hydrolyzable groups from chains and/or rings. Because most ofthe silanes suitable for the invention have only one group that isbonded by carbon to silicon and that carries either a polymerizable C═Cdouble bond or a sulfonate group or sulfate group, they have, in case ofthe presence of only two hydrolyzable groups/OH groups, generally one ofthe afore mentioned groups which are referred to as network modifiers

It can be desirable to provide additional metal compounds for theincorporation by condensation into the inorganic network. For thispurpose, in particular hydrolytically condensable compounds of metals ofthe main groups III and IV as well as of the transition metal groups IIIto VI are suitable, e.g., of boron, aluminum, titanium germanium,zirconium or tin. These metal compounds are known in large numbers. Inthese cases, a silicic acid (hetero) polycondensate is generated inwhich the afore mentioned metal atoms are integrated into the Si—O—Sinetwork. The additional metal compounds are often alkoxy compounds; inspecific embodiments of the invention, the other metal compoundsthemselves can also have reactive groups however. In this context, ofspecial interest for the present invention are complexes whichthemselves carry (meth)acryl groups because the latter can be integratedby a subsequent organic polymerization into the organic network.

The preparation of the polycondensates can be divided in principle intotwo groups: According to variant (A), different silanes are provided orgenerated wherein at least one of them has a sulfonate group or asulfate group and at least a second one has an organically polymerizablegroup that has at least one C═C double bond. In contrast to this,according to variant (B), a polycondensate of one or several silanes isgenerated first which does not yet have all groups necessary for theinvention, and then a modification is carried out at the stage of thepolycondensate which produces the polycondensate according to theinvention.

The variant (A) can be carried out with the aid of a plurality ofstarting silanes that are partly commercially available, partly can beprepared easily by a person of skill in the art. For example, amethacryl silyl ester can be obtained easily by reaction of a suitablesilyl alcohol with methacrylic acid chloride or of a suitable silylepoxide with methacrylic acid. Other starting silanes are described, forexample, in DE 40 11 044 C1 and DE 44 16 857 C1. It is advantageous thatalso such silanes can be used which have more than one group containinga C═C double bond and/or more than one sulf(on)ate group which arepreferably located at the same residue that is bonded by carbon to thesilicon. One example for this is following (reaction 7):

Reaction 7:

The N-methacryl-modified methacrylsilylamide residue used herein can beproduced in that a silane with a hydrocarbon group that is bonded by acarbon atom to the Si atom is provided and that carries a primary aminogroup and a secondary amino group and is reacted with activatedmethacrylic acid (e.g., methacryloyl chloride or anhydride). Variantscan be produced in that instead of the primary amine a hydroxyl group ora thiol group is present and/or in that instead of the secondary amine aside group with a primary amine, a hydroxyl group or a thiol group ispresent. Examples of suitable aminosilanes are the compounds (aminoethylaminomethyl) phenylethyl trimethoxysilane,N-(2-aminoethyl)-3-aminopropyl-methyldimethoxysilane,N-(2-aminoethyl-3-aminopropyl) trimethoxysilane,N-2-aminoethyl-3-aminopropyl tris(2-ethylhexoxy)silane,6-(aminohexylaminopropyl) trimethoxysilane,N-(N′-(2-aminoethyl)aminoethyl)-3-aminopropyl trimethoxysilane,N-(N′-(2-aminoethyl)aminoethyl)-3-aminopropyl methyldimethoxysilane,N-(N′-(2-aminoethyl) aminoethyl)-3-aminopropyl triethoxysilane,N-(N′-(2-aminoethyl)aminoethyl)-3-aminopropyl methyldiethoxysilane,N-(N′-(2-aminoethyl)aminoethyl)-3-aminopropyl trimethylsilane,N-(N′-(2-aminoethyl)aminoethyl)-3-aminopropyltris(methoxyethoxyethoxy)silane. Analogous compounds with correspondinghydroxyl groups or thiol groups are disclosed in EP 0 779 890 A1 , forexample. The hydrocarbon group can also have another configuration thanin the examples presented above.

It is evident that, instead of a silyl group with two functional groupswhich can be reacted with (meth)acrylic acid, also one with three oreven more such functional groups can be used. The (meth)acrylsilaneswhich are obtainable, respectively, enable due to their respectiveavailable number of (meth)acryl groups an adjustability of the densityof the organic network obtainable by the future polymerization. Ofcourse, the number and the chemical structure of the residues RO inreaction 7 can be selected as defined above; the definition “R=Me/Et” inwhich Me means methyl and Et means Ethyl, are purely exemplary.

The silylsulfonate can be prepared, for example, by reaction ofallylsulfonate with a hydridosilane or by reaction of sodium sulfitewith an epoxysilane. The sulf(on)ate silane can also be modifiedarbitrarily. For example, the sulfonic acid group of the correspondingsilane can be connected with the silicon atom by means of a carbon chainthat is interrupted by oxygen atoms and/or amino groups. Such silanescan be obtained by reaction of an epoxy-containing silane with sodiumsulfite, aminoethane sulfonate, methylaminoethane sulfonate or the like,as is evident for example from the reaction 6 discussed infra in whichthese reactions are carried out, however, only after the hydrolyticcondensation of the respective silanes. When sodium sulfate is usedinstead of sodium sulfite, as for example disclosed in U.S. Pat. No.6,777,521, a corresponding sulfate is obtained.

According to variant (B), a condensate is prepared either from only onesilane which carries however not all invention-relevant groups, whereinafterwards only some of the groups that are bonded by carbon to thesilicon are modified with a suitable reaction partner (variant B1),mostly by introduction of a sulfonic acid group or sulfonate group, ortwo or even more silanes are used for the preparation of the condensatewherein at least one of the silanes is modified afterwards (variant B2),also mostly by introduction of a sulfonic acid group or sulfonate group.

The variant (B1) has the advantage that it is possible to adjustarbitrarily the ratio of the groups with polymerizable double bondsrelative to the groups with sulf(on)ate by varying the amount of addedsulfonic acid compound. An example of this variant is shown in thefollowing reaction 5:

Reaction 5:

In the preparation of condensates according to variant (B), alreadyknown compounds can also be employed, of course, or known reactionsequences can be used because known (meth)acrylsilanes as well as knownsulfonate group-containing silanes can be used. The preparation ofcondensates as shown in stage 1 of reaction 5 is already known from DE44 16 857. Afterwards, some of the methacrylate residues are used forattaching a sulfonate group; in the example, a thioalkane sulfonic acidis used for this purpose. In this concrete example, it is important ofcourse that the thioalkane sulfonic acid is used in less thanstoichiometric amounts in order to preserve some (meth)acrylate groups.The advantage of a reaction as in this example resides in that the ratioof (meth)acrylate groups to sulfonic acid groups or sulfate groups inthe condensate can be selected arbitrarily. Another advantage resides inthat the hydroxyl group can be preserved that resulted from the ringopening of the epoxide because it must not be used for the attachment ofthe (meth)acrylate. Hence, it can be used for other purposes, e.g., forincreasing the matrix hydrophilicity of the silicic acid polycondensatesor for the attachment of other reactive groups, for example, of afurther (meth)acrylate group.

Of course, this reaction can be modified in any manner by an easyexchange of substituents for other substituents, as is known from theart. Accordingly, an aminosilane can be used instead of an epoxysilane,for example, so that the methacryl group is present in the form of themethacrylamide. As described above in relation to variant (A), thesilane used as a starting material can contain of course also severalreactive groups which can react with activated (meth)acrylic acid, or asilane is used from the start which carries a (non-activated) doublebond, for example, a vinyl silane or allyl silane. Another variant isthe exchange of the methacrylic acid by a bridged ring system such as anorbornene group which can be obtained by conversion of cyclopentadiene;see the following reaction:

With regard to employable norbornene silane and related compounds,reference is being had to DE 196 27 198 A1. Thus, the norbornene ringshown at the top in the reaction scheme can be optionally substituted,of course; also a bicyclo[2.2.2]octene residue can be present instead ofthe norbornene residue (i.e., of bicyclo[2.2.1]heptane residue).Furthermore, the double bond-containing five-membered ring of thecondensed system can contain an oxygen atom when the (meth)acryl groupis reacted with furan instead of cyclopentadiene.

The variant (B2) can be explained by means of the following scheme:

This reaction scheme shows the co-condensation of two silanes whereinone of them carries a (meth)acryl group, the other a strained heteroring. The hydrolytic condensation can be carried out in a known mannerin such a way that the hetero ring remains closed. A sulfonate group isattached after the condensation reaction to the hetero ring. When thisis done according to b) by means of the attachment by means of an aminogroup, the reaction can be carried out easily—and also in knownmanner—in such a way that the amino group does not attack or does hardlyattack the double bond of the methacryl group.

According to the reaction scheme a condensate according to the inventionis produced as describe above. With a reaction carried out in this way,the ratio of (meth)acryl groups to sulf(on)ate groups can be determinedby the ratio of the employed silanes relative to each other.Incidentally, the same or comparable reaction types as described supracan be also used.

Instead of a methacryl group as shown herein, other C═C doublebond-containing groups which are bonded in any manner to the respectivesilicon atom can be used of course. A small selection is shown in thefollowing scheme:

Reaction 6:

The use of a silane which was obtained as shown in reaction 5, step 1,by reaction of an epolysilane with methacrylic acid is anotheralternative. In this alternative, step 2, the hydrolytic condensation,does not follow immediately after the preparation of the silane, asshown in reaction 5, but the methacrylated silane is mixed withadditional epoxysilane and the mixture of epoxysilane withmethacrylsilane is subjected to the hydrolytic condensation, as shown inreaction 6.

The silicic acid (hetero) polycondensates according to the invention cancarry other functional groups which can impart to them advantageousproperties for special applications. Foremost, carboxylic acid group andhydroxyl groups are to be named in this context. Examples of thepresence of hydroxyl groups are found in the preceding reactions 5, 6and in the scheme concerning the variant B2. They can be obtained, forexample, in that an additional silane carrying such a group isco-condensed with the remaining starting silanes. Instead, a silane canbe used which has, in addition to this group, a polymerizable C═C doublebond and/or a sulf(on)ate group, namely optionally at the same groupthat is bonded by carbon to the silicon. Suitable silanes will bedescribed infra.

All silicic acid (hetero) polycondensates according to the invention,independent of whether prepared according to variant (A) or one of thevariants (B), can be produced additionally with use of at least onesilane having a residue that is bonded by carbon to the silicon and hasan organically polymerizable C═C double bond as well as a sulf(on)ategroup. This silane can be represented, for example, by the formula (I)

R¹ _(a)R² _(b)SiZ_(4-a-b)  (I)

wherein R¹ is a hydrolytically condensable residue; R² an alkyl, aryl,arylalkyl, alkylaryl or alkylarylalkyl that is substituted orunsubstituted, straight-chain, branched or has at least one cyclicstructure, as an exception it can be instead a corresponding alkenyl orcan encompass an alkenyl whose carbon chain in all cases optionally canbe interrupted by —O—, —S—, —NH—, —S(O)—, —C(O)NH—, —NHC(O)—,—C(O)O——C(O)S, —NHC(O)NH— or C(O)NHC(O) groups which can optionally beoriented in both possible directions; Z is a residue in which arepresent at least one (meth)acryl group and at least either a sulfonategroup or a sulfate group that are bonded directly or indirectly by anunsubstituted or substituted hydrocarbon group to the silicon atom; a is1, 2 or 3; b is 0, 1 or 2; and a+b together are 2 or 3. In particular,it is preferred that the residues Z furthermore have in each case atleast one hydroxyl group or a carboxylic acid group or an ester derivedtherefore or a corresponding salt.

In several preferred embodiments, the silanes of the formula (I) can berepresented by the following formula (Ia):

wherein:R¹ is a hydrolytically condensable residue,R³ is an alkylene that is unsubstituted or substituted with a functionalgroup, straight-chain, branched or has at least one cyclic structure,A is a linking group,R⁴ is an alkylene that is optionally interrupted by O, S, NH or NR⁸and/or optionally functionally substituted,M is hydrogen or a monovalent metal cation or the corresponding portionof a multi-valent metal cation, preferably selected from alkali cationsand alkaline earth cations, in particular from Na, K, ½ Ca, ½ Mg, orammonium is,

R⁵ and R⁶, independently of each other, either have the meaning of R¹ orare alkyl, aryl, arylalkyl, alkylaryl or alkylarylalkyl, substituted orunsubstituted, straight-chain, branched or having at least one cyclicstructure, or can be instead in exceptions also a corresponding alkenyl,arylalkenyl or alkenylaryl,

R⁷ is a hydrocarbon group, as has been defined supra, bonded by a carbonatom to the silicon atom,R⁸ is C₁-C₆ alkyl or (meth)acryl,B is vinyl, 2-allyl or, in case of e>1, an organic residue with e vinylgroups present in each case bonded to a group located in the curlybrackets,Y is a nitrogen atom, —O—CH═, —S—CH═ or —NH—CH═, and in each case theoxygen atom, the sulfur atom or the NH group has a bond to theneighboring C(O) group,b is=0 or 1,c is=0 or 1,with the proviso that, for the combination of Y being a nitrogen atom,b=0, c=0, and d=0, the residue R³ is ethylene, and with proviso that,for the combination of Y being a nitrogen atom, b=0, c=1, and d=0, theresidue R⁴ is an alkylene that is interrupted by O, S, NH or NR⁸ andoptionally functionally substituted,d is=0 or 1, ande is=1, 2 or 3.

The linking group A in the formula (la) is preferably selected from(read from the left to the right in the formula la) C(O)NH, NHC(O),NR⁸C(O), C(O)O, and OC(O), and R⁸ is defined as above. In special cases,the linking group A can have these groups oriented however in adirection opposite to the reading direction and can be selectedadditionally from NHC(O)O, NR⁸C(O)O, NHC(O)NH, C(O)NHC(O), and C(O)S.The residue R⁴ is substituted in specific embodiments with at least onehydroxyl group and/or with a residue R⁹COOM, wherein R⁹ is a chemicalbond or a C₁-C₆ alkylene residue and M is hydrogen or a monovalent metalcation or the corresponding portion of multi-valent metal cation,preferably selected from alkali cations and alkaline earth cations, inparticular from Na, K, ½ Ca, ½ Mg, or ammonium.

With few exceptions, the syntheses for the preparation of the silanes ofthe formula (I) or (Ia) are controlled such that for the addition of thesulfonic acid group or sulfate group to the molecule that alreadycontains a (meth)acryl group a C═C double bond is available. As desired,to the latter either sodium sulfite or a sulfonic acid with a residuethat is easily reacted by addition, such as hydroxyl, thio oraminoalkane sulfonic acid, can be added. Alternatively, the attachmentof the sulfonic acid group can also be carried out by the reverseprinciple in that hydroxyl, thio or aminoalkylsilane is reacted with analkylene sulfonic acid. With this process, a chain length extension bythe carbon atoms of the alkylene group is of course inevitable, which isthe reason why the first variant is preferred over the second. Finally,there is still the possibility to cause ring opening of a strainedhetero ring, in particular of a three-membered ring, with sulfite or ahydroxyl, thio or aminoalkane sulfonic acid. This variant has theadvantage that the ring opening reaction generates another reactivegroup which can be used for the subsequent attachment of the activated(meth)acrylic acid. The three-member ring can be opened alternativelyalso by means of a sulfate; in these cases, a sulfate group-containingproduct is obtained.

All together, three basic variants for the production of the silaneswith the formula (I) are available according to the invention asfollows:

Variant (i):

-   -   a. a silane with a hydrocarbon group bonded by a carbon atom to        the Si atom is provided which carries at least two functional        groups, selected from primary amines, secondary amines, hydroxyl        groups and thiol groups,    -   b. a first one of the two functional groups is reacted with        optionally activated (meth)acrylic acid and the second one of        the two functional groups is reacted with an optionally        activated second carboxylic acid having a C═C double bond and        optionally at least one other functionality, and    -   c. subsequent to the aforementioned reaction, a sulfonate        group-containing or sulfate group-containing compound or a        sulfite is added to the C═C double bond of the carboxylic acid        residue reacted with the second functional group in such a way        that at the (meth)acryl residue reacted with the first one of        the two functional groups such an addition does not take place,        which can be ensured in different ways, e.g., by the molar ratio        of the groups reacted with each other, wherein the second        carboxylic acid having a C═C double bond can be a (meth)acrylic        acid or another double bond-containing carboxylic acid.

Variant (ii):

-   -   a. a silane with a hydrocarbon group bonded by a carbon atom to        the Si atom is provided which carries at least one reactive        hetero ring, selected from the three-membered rings        oxacycyclopropyl (=epoxy), azacyclopropyl and thiocyclopropyl        and cyclic carbonates (the latter can be obtained by reaction of        an epoxy ring with CO₂, but also by other pathways, as disclosed        in DE 44 23811 in detail),    -   b. the hetero ring is reacted with a sulfite or a sulfate or a        sulfonate group-containing or a sulfate group-containing        compound, and    -   c. at least the OH, SH or NH₂ group that is obtained in this way        is reacted with (meth)acrylic acid that is optionally activated.        Variant (iii)    -   a. a silane with a hydrocarbon group bonded by a carbon atom to        the Si atom is provided which has an amino group or a mercapto        group,    -   b. an alkenyl sulfonate or a sulfone is reacted with the amino        group or the mercapto group, and    -   c. the secondary amino group or thio group produced in b. is        reacted with (meth) acrylic acid that is optionally activated.

An example of the preparation of such a silane according to variant (i)is shown below in an exemplary way by means of the reaction 1:

A reaction according to variant (ii) is shown below in an exemplary wayby means of the reaction 3:

Reactions 3a and 3B:

A conversion according to variant (iii) is shown below in an exemplaryway by means of the reaction 4;

Reaction 4.

The preceding reaction examples show conversions to suifonates. By theuse of sulfates, as disclosed in U.S. Pat. No. 6,777,521, instead ofsulfites in the reactions according to variant (ii), the correspondingsulfate compounds can be obtained.

The syntheses for producing the silicic acid (hetero) polycondensatesaccording to the invention are characterized in all variants by thesimplicity of the reaction control, a low number of working steps, andgood yields.

As partially already mentioned above, in specific embodiments of theinvention a hydrocarbon residue bonded to a silicon atom can besubstituted with more than one sulfonic acid group or sulfuric acidgroup and/or with more than one (meth)acryl group. By the presence ofmore than one (meth)acryl group the network which forms uponpolymerization of the condensates can become even more fine-meshed. Inthis connection, is should be noted that by the contents ofpolymerizable double bonds the modulus of elasticity of the futureorganically polymerized polymer can be adjusted in such a way that thepolymer becomes more or less flexible and thereby less hard or harder.By the presence of more than one sulfonic acid group or sulfuric acidgroup the etching effect of the condensate is further increased.

The inventors have surprisingly found that already with low sulfonicacid contents an enormous etching effect on the dental tissue can beobserved. This can be demonstrated by means of a comparison of theaverage roughness of the enamel surface: Polished enamel has an averageroughness of about 0.21 μm, measured with an optical profilometer of thecompany UBM. With a phosphonic acid-functionalized silicic acidpolycondensate of glycerin-l-methacryloyl-2-(siloxypropyl) carboxymethylphosphonic acid, roughness in the range of 0.33 can be achieved. Withcondensates of the compounds according to the invention, the roughnessis within the range of more than 0.45 μm. Dental enamel images are shownin the FIGS. 1 a and 1 b.

The versatility and the specific adaptation possibility to therespective purpose of the silicic acid (hetero) polycondensatesaccording to the invention and the polymers configured or formedtherefrom are based quite substantially on the indicated preparationpossibilities. Hence, the use of additional monomers, e.g., the use ofreactive diluting agents with the goal of a sufficient organiccrosslinking of the polymers, can therefore often be dispensed with.This is an advantage in particular when the condensates according to theinventions and the polymers available therefrom are to be used in themedical field, e.g. dental field. For it is known from the increasingpublic discussion of the subject matter, that (meth)acrylate-basedmonomers are suspected of triggering allergies.

The inventors, moreover, were surprised by the fact that the silicicacid polycondensates according to the invention are generallywater-soluble, even through they carry a large number of (meth)acrylategroups and have an inorganically condensed structure. This has greatadvantages for many applications, wherein medical applications are to bementioned foremost. For the condensates can be applied in aqueousmedium, i.e. can be applied in any form without the use of a non-aqueoussolvent being required. But also for industrial applications water-basedreactions are always advantageous, namely already for reasons ofoccupational safety and the environmental compatibility.

The possibility of forming other reactive groups in the silanes besidesthe sulfonic acid functional group opens up additional possibilities.Thus, sulfonic acid groups have a stronger etching effect than carboxylgroups while the latter have complexing properties. Should there beadditional hydroxyl groups, these can be used either for improvingwetting at the base surface or for further reactions which can furthermodify the silicic acid (hetero) polysiloxanes according to theinvention. One example is complexing or reacting with a dicarboxylicacid (which can be caused, e.g., by means of appropriately activatedacid molecules).

In addition to degree of polymerization and etching effect, the groupsand residues located according to the invention on the polycondensatesof the invention have further properties which are favorable for severalintended purposes: The sulfonate group or sulfate group is a chargecarrier for which reason uses are possible as electrophoresis gels, asmaterials for the electrophoretic coating or as materials that modifyconductivity or antistatic properties. Moreover, the group can serve asan acidic catalyst, namely, on the one hand, for the sol gel process (alater separation step to the catalyst separation can then be dispensedwith) and, on the other hand, in respect to the future use (an exampleare the mesoporous membranes with sulfonic acid groups which can serveas catalyst for chemical processes). The group provides furthermore agood solubility in polar media. Particularly for dental purposes, butnot exclusively for this purpose, it serves as an adhesion promotinggroup for inorganic, organic as well as hybrid surfaces. Like carboxylicacid groups, it can also form ionic bonds by means of which e.g.,alkali, earth alkali, ammonium, Ti, Zr, Sn, Ca and other suitablecations can be incorporated in the form of their salts into thepolycondensate network. In this way, several modification ormaterial-specific adjustments, e.g., concerning the X-ray opacity, therefractive index or the contact toxicity, can be achieved. By thesulfonate groups or sulfate groups in the material, the material ismoreover imparted with an antimicrobial effect. But the invention can beapplied also in quite different fields because e.g. proton-conductingmembranes, e.g., for fuel cells, can be formed with sulfonategroup-containing or sulfate group-containing materials. Further, thematerials are suitable e.g. as an ion exchanger, as a pseudo-staticphase in the electrokinetic chromatography or as substances withinterfacial tension lowering action (detergent).

The use in the medical sector (specifically dental field), e.g., as anadhesive promoting agent (monomer-free bonding) and as a matrixcomponent for cements, is in particular favored by the combination ofthe sulfonate groups or sulfate groups and optionally additionally bythe —CO₂H groups with polymerizable/polyadditive double bonds in amolecule.

The quantitative proportion of C═C double bond-containing silane tosulf(on)ate-containing silane in the condensate according to theinvention is basically not critical. Thus, the number of the C═C doublebond-containing residues that are bonded by carbon to silicon to thenumber sulf(on)ate-containing residues bonded by carbon to silicon canbe, for example, in the range of 10:1 to 1:10. Particularly preferred isa ratio of 3:1 to 1:1, and often a ratio of about 1:1 will be selected.Ratios in which the number of the C═C double bond-containing residuespredominates in comparison to the number of sulf(on)ate-containinggroups are preferred in several cases because then an especially tightorganic network can be generated. The same goal can be achieved ofcourse also in that those groups are used that are bonded by carbonatoms to the silicon and that carry more than one C═C double bond.

By use of any fillers (particles, fibers), as the particles describedfor example in DE 196 43 781, DE 198 32 965, DE 100 18 405, DE 104 1038, DE 10 2005 018 351, DE 10 2005 061 965 as well as in DE 10 2005 053721, or of SiO₂ particles in combination with the silicic acid (hetero)polycondensates according to the invention, the corresponding compositesare obtained. SiO₂ particles, for example, can be obtained by known solgel processes; they can have a very narrow diameter distribution. Theseor also differently composed nanoparticles can be modified on theirsurface, e.g., silanized, in order to adapt their surface properties tothose of the matrix.

The composites can be plastically processed and are characterized byvery high filler concentrations that are possible (see nanohybridecomposites) in combination with an excellent processibility. Therefore,different properties can be adjusted in wide ranges for the resultantsilanes, resin systems, matrix systems as well as for the filled systems(composites) and adapted to the requirements.

Particularly preferred is the use of the invention in the dental field,i.e., as an adhesive, for example. In this context, the silicic acid(hetero) polycondensate obtained by hydrolytic condensation from thesilanes according to the invention can be mixed with one or severaladditives and/or fillers, in particular for the production by dentalcomposites, before organic curing. An essential component in this regardare nanoparticulate fillers or a combination of such fillers ofdifferent size or different composition, as mentioned above, optionallyin combination with other known fillers like particulate dental glasses,e.g., Ba—Sr aluminum borosilicates.

The filler can be added according to the desired field of application invery different total quantities. Thus, adhesives need only relativelysmall filler amounts. Also, fissure sealers, coatings for the neck ofthe tooth, and the like contain in general a proportion of less than 50wt. %, e.g., 1-50 wt. % and preferably from approx. 1 to 20 wt. % of afiller. In other cases, the filler can be present optionally e.g. in aproportion of 50 wt. % of the composite, or even clearly above that, andin particular in a proportion of 70 to 90 wt. % of the composite whenhigher filled or highly filled composites are needed, e.g., for fillingsand the like.

In accordance with the intended special purpose of use, suitableadditives can be added to the silicic acid (hetero) polycondensates orthe composite of the invention, such as initiators, coloring agents(dyes or pigments), oxidation inhibitors, polymerization inhibitors (foravoiding a premature polymerization), leveling agents, UV absorber,stabilizers, microbiocidal active ingredients or the like, as is knownto a person of skill in the art. Examples of polymerization initiatorsare initiators for radical polymerization, namely for thermal curinglike peroxides (e.g., benzoyl peroxide) or photo initiators likebenzophenone, camphorquinone or combinations of a-diketones with amineas a reducing agent, as for example disclosed in DE 199 03 177 C2. Forthe dual curing of radically and cationically polymerizable systems, inparticular diaryl iodonium or triaryl sulfonium salts can be added forwhich the aforementioned publication also provides examples.

The filled dental composite (i.e. the organically not yet crosslinkedfilled resin), after it has been applied for the intended purpose, canbe crosslinked in suitable manner organically and thus be cured. Aboveall, an organic polymerization of the (meth)acrylate groups is used forthis purpose. This is a radical polymerization that usually occurs withaddition of radical starters like the above mentioned ones andoptionally known activators, with exposure to e.g. visible light (bluelight; dental irradiator), i.e. photochemically, thermally orredox-induced, but also occurs within the scope of 2-component reactionsor anaerobically. The combination of self curing action with e.g.photo-induced or thermal curing is also possible.

However, the use of the silicic acid (hetero) polycondensates accordingto the invention applies not only to composites adapted for dentalpurposes, but inter alia also to the use in the form of bulk materials,(dental) cements, adhesives, potting compounds, coating materials,adhesion promoters, binding agents for ceramic particles (ceramicshaping processes), producing or priming of fillers and fibers, use inreaction extruders and the like for most different purposes (inparticular for medical, but also for (micro)optical and(micro)electronic applications). The condensates can be converted bymeans of a large number of processes into structured surfaces or bodies,for example, by silk screen printing, inkjet printing, direct laserwriting, photo lithography or two-photon or multi-photon polymerization.

Below, the invention will be explained with the aid of examples in moredetail.

EXAMPLE 1 Preparation of a Silicic Acid Polycondensate According toVariant A

To a solution of 3.4 g (0.01 mol) N,N′dimethacryloyl-3-(2-aminoethylamino)-propylmethyl dimethoxysilane inacetone/water (ratio 1:1), 2.5 g (0.01 mol) 3-trimethoxysilylpropylsulfonic acid were added and stirred at 40° C. until the condensationwas complete. Afterwards the volatile components were removed undervacuum.

EXAMPLE 2 Preparation of a Silicic Acid Polycondensate According toVariant B1 (Reaction 5)

Stage 1: 3.93 g (0.015 mol) triphenyl phosphine and 0.316 g (0.06 wt. %)butylhydroxyl toluene were dissolved in 377.8 g (1.521 mol)diethoxy(3-glycidyloxypropyl) methylsilane. Afterwards, the solution washeated to 85° C. and 142.05 g (1.65 mol) methacrylic acid added dropwiseduring 1.5 h. After 24 h at reflux, the product was dissolved in ethylacetate and was adjusted with 1N hydrochloric acid to pH 1-2. After 3 d,the solution was washed with 1 N sodium hydroxide solution up to a pHvalue of 12 and, afterwards, the volatile components removed undervacuum.

Stage 2: To a solution of 7.78 g (0.008 mol) product of the stage 1,0.68 g NaOH in 40 ml ethanol, 1.33 g (0.008 mol) sodium 2-mercaptoethanesulfonate in 40 ml H₂O was added dropwise at 50° C. After 19 h, ethanolwas removed at 40° C. under vacuum, and the aqueous solution waspurified twice with ethyl acetate. The aqueous phase was treated with acation exchanger and, afterwards, the volatile components were removedunder vacuum. The product can be redissolved in water.

Average roughness R_(a)=0.45 μm (on enamel)

EXAMPLE 3 Preparation of a silicic acid polycondensate according tovariant B2:

Stage 1: To a solution of 2.2 g (0.01 mol) methacryloxypropyltrimethoxysilane in 50 ml ethyl acetate, 2.2 g (0.01 mol)3-glycidoxypropyl methyldimethoxysilane were added. After addition of awell-established catalyst, as for example ammonium fluoride, thereaction mixture was stirred at 40 ° C. until the condensation wascomplete. After usual work-up, e.g., extraction with water, the volatilecomponents were removed under vacuum.

Stage 2: The co-condensate of stage 1 was dissolved in 20 ml ethanol andwas heated to 80° C. A solution of (0.01 mol) sodium bisulfite in 20 mlwater was added dropwise and the reaction mixture was stirred underreflux for 4 h. After evaporation of ethanol, the aqueous phase waspurified with ethyl acetate, treated with a cation exchanger, andafterwards the volatile components were removed under vacuum.

EXAMPLE 4 Preparation of a Silane with a Group that is Gonded by Carbonto the Silicon and Carries a C═C Double Bond and a Sulfonate Group

Stage 1: 5.11 g (0.024 mol) N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane was dissolved in 5.21 g triethylamine and 30 mltoluene and was cooled to 0° C. Afterwards, 5.0 ml (0.051 mol)methacrylic acid chloride in 30 ml toluene were added dropwise. Thereaction mixture was stirred for 3 h at room temperature. The mixturewas centrifuged, and the obtained solution adjusted with 1N hydrochloricacid to pH 1-2. After 24 h, the volatile components were removed undervacuum.

Stage 2: 3.92 g (0.013 mol) of the product of stage 1 were dissolved in30 ml ethanol, the solution adjusted with sodium hydroxide to pH 10, andheated to 60° C. Afterwards, 1.93 g (0.015 mol) sodium 2-mercaptoethanesulfonate dissolved in 40 ml H₂O were added dropwise, followed bystirring for 4 h. Ethanol was removed under vacuum and the aqueoussolution treated with a cation exchanger. The volatile components wereremoved under vacuum. The product is a water-soluble solid.

Average roughness R_(a)=0.58 μm (on enamel)

EXAMPLE 5 Preparation of a Silane with a Group Bonded by Carbon toSilicon and Carrying A C═C Double Bond and a Sulfonate Group

Stage 1: 8.69 g (0.042 mol) N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane were dissolved in 50 ml ethyl acetate and heatedto 50° C. A solution of 4.23 g (0.043 mol) maleic acid anhydride in 30ml ethyl acetate was added dropwise, followed by stirring for 19 h. Themixture was centrifuged and the residue was purified twice with ethylacetate and was dried under vacuum.

Stage 2: 6.06 g (0.021 mol) of the product of the stage 1 were dissolvedin 5 ml water and 1.72 g NaOH and cooled to 0° C. 2.1 ml (0.021 mol)methacrylic acid chloride were slowly added dropwise with strongstirring action, followed by stirring for 5 h at 50° C. Afterwards thevolatile components were removed under vacuum.

Stage 3: 9.82 g (0.021 mol) of the product of the stage 2 were dissolvedin 20 ml water and heated to 60 ° . Afterwards, 2.61 g (0.021 mol)sodium sulfite were added dropwise under stirring, followed by stirringfor 24 h. The aqueous solution was treated with a cation exchanger andthe volatile components were removed under vacuum. The product can beredissolved in water.

Average roughness R_(a)=0.48 μm (on enamel)

EXAMPLE 6 Preparation of a Silane with a Group Bonded by Carbon toSilicon and Carrying a C═C Double Bond and a Sulfonate Group

Stage 1: 5.04 g (0.040 mol) sodium sulfite were dissolved in 30 ml H₂Oand heated to 80° C. A solution of 9.96 g (0.040 mol) 3-glycidoxypropylmethyldiethoxysilane in 10 ml ethanol was added dropwise and stirred for3 h under reflux.

After evaporation of ethanol the aqueous phase was purified with ethylacetate, and the volatile components were removed under vacuum.

Stage 2: 5.04 g (0.016 mol) of the product of the stage 1 was dissolvedin 10 ml water and 2.79 g (0.070Ehiol) NaOH and cooled to 0° C.Afterwards, 4.0 ml (0.016 mol) methacrylic acid chloride were addeddropwise, and the reaction mixture was stirred for 4 h at 30° C. Thesolution was purified with ethyl acetate, the aqueous phase treated witha cation exchanger, and the volatile components removed afterwards undervacuum. The product is water-soluble.

What is claimed is:
 1. to
 16. (canceled)
 17. A silicic acid (hetero)polycondensate of: at least one silane with a first residue bonded by acarbon atom to silicon and carrying an organically polymerizable C═Cdouble bond; at least one silane with a second residue bonded by acarbon atom to silicon and carrying a sulfonate group or sulfate groupof the formula —(O)_(d)—SO₃M with d=0 or 1 and with M=hydrogen or amonovalent metal cation or the corresponding portion of a multi-valentmetal cation; with the proviso that polycondensates in which the C═Cdouble bonds are formed exclusively by methacrylic esters attached inthe form of a methylene acrylic ester group to the groups that arebonded by a carbon to silicon are excluded.
 18. The silicic acid(hetero) polycondensate according to claim 17, wherein the organicallypolymerizable C═C double bond is a vinyl group or is a part of an allylgroup, an acryl group, a methacryl group, an optionally substitutedbicyclo[2.2.1] heptene group, an optionally substitutedbicyclo[2.2.2]octene group, or an optionally substitutedoxabicyclo[2.2.1]heptene group.
 19. The silicic acid (hetero)polycondensate according to claim 17, further comprising third residuesbonded by a carbon atom to silicon and each carrying at least onecarboxylic acid group or an ester derived from the least one carboxylicacid group or a corresponding salt of the least one carboxylic acidgroup or a hydroxyl group, wherein said third residues can be identicalwith the first and second residues as defined in claim 1 or can bedifferent.
 20. The silicic acid (hetero) polycondensate according toclaim 19, wherein the third residues, carrying at least one carboxylicacid group or a hydroxyl group, carry additionally either an organicallypolymerizable C═C double bond or a sulfonate group or a sulfate group,but not a combination thereof.
 21. The silicic acid (hetero)polycondensate according claim 20, wherein the third residues bonded bya carbon atom to silicon are at least partially an alkylene group, anarylene group or an alkylaryl group, wherein the alkylene group, thearylene group, and the alkylaryl group each can be interruptedoptionally by one or several groups selected from —O—, —S—, —NH—,—S(O)—, C(O)NH—, —NHC(O)—, —C(O)O—, —C(O)S, —NHC(O)NH—, and—C(O)NHC(O)—.
 22. The silicic acid (hetero) polycondensate according toclaim 17, wherein the first and second residues bonded by a carbon atomto silicon are at least partially an alkylene group, an arylene group oran alkylaryl group, wherein the alkylene group, the arylene group, andthe alkylaryl group each can be interrupted optionally by one or severalgroups selected from —O—, —S—, —NH—, S(O)—, —C(O)NH—, —NHC(O)—, —C(O)O—,—C(O)S, —NHC(O)NH—, and C(O)NHC(O)—.
 23. The silicic acid (hetero)polycondensate according to claim 17, further comprising a silane with afourth residue bonded by a carbon atom to silicon and carrying anorganically polymerizable C═C double bond and further carrying asulfonate group or a sulfate group.
 24. The silicic acid (hetero)polycondensate according to claim 23, wherein the first and secondresidues bonded by a carbon atom to silicon are at least partially analkylene group, an arylene group or an alkylaryl group, wherein thealkylene group, the arylene group, and the alkylaryl group each can beinterrupted optionally by one or several groups selected from —O—, —S—,—NH—, —S(O)—, —C(O)NH—, —NHC(O)—, —C(O)O—, —C(O)S, —NHC(O)NH—, and—C(O)NHC(O)—.
 25. The silicic acid (hetero) polycondensate according toclaim 17, made by using additionally at least one hydrolyticallycondensable metal compound of a metal, selected from metals of the maingroups Ill and IV and metals of the transition metal groups III to VI.26. The silicic acid (hetero) polycondensate according to claim 17,wherein the silicic acid (hetero) polycondensate is water-soluble. 27.The silicic acid (hetero) polycondensate according to claim 17 as adental material or dental adhesive.
 28. A composite, comprising asilicic acid (hetero) polycondensate according to claim 17 and a fillerincorporated into the silicic acid (hetero) polycondensate.
 29. Thecomposite according to claim 28 as a dental material or dental adhesive.30. A polymerisate obtained from a silicic acid (hetero) polycondensateof claim 17 by polymerization of at least some (meth)acryl groupscontained in said silicic acid (hetero) polycondensate.
 31. Thepolymerisate according to claim 30 as a dental material or dentaladhesive.
 32. A method for preparing a silicic acid (hetero)polycondensate according to claim 17, comprising the steps of: providingat least one silane with a first residue that is bonded by a carbon atomto silicon and that carries an organically polymerizable C═C doublebond, wherein the at least one silane with the first residue ishydrolytically condensable, with the proviso that no silanes in whichthe C═C double bonds are formed exclusively by methacrylic esters whichare attached in the form of a methylene acrylic ester group to thegroups that are bonded by a carbon to silicon, are provided; providingat least one silane with a second residue that is bonded by a carbonatom to silicon and that carries a sulfonate group or sulfate group ofthe formula —(O)_(d)—SO₃M with d=0 or 1 and with M=hydrogen or amonovalent metal cation or a corresponding portion of a multi-valentmetal cation, wherein the at least one silane with the second residue ishydrolytically condensable; and co-condensing the at least one silanewith the first residue and the at least one silane with the secondresidue under hydrolytic conditions.
 33. The method according to claim32, carrying out the step of co-condensing by a sol gel process.
 34. Amethod for preparing a silicic acid (hetero) polycondensate according toclaim 17, comprising the steps of: generating or providing a silicicacid polycondensate of at least one silane with a first residue bondedby a carbon atom to silicon and carrying an organically polymerizableC═C double bond, with the proviso that no silanes in which the C═Cdouble bonds are formed exclusively by methylene acrylic esters aregenerated or provided; and reacting only a portion of the at least onesilane with said first residue with a compound which carries asulf(on)ate group and can attack at the organically polymerizable C═Cdouble bond so that some of the groups containing the organicallypolymerizable C═C double bond are reacted to a sulf(on)ate-containinggroup.
 35. The method according to claim 34, wherein the organicallypolymerizable C═C double bond is a vinyl group or is a part of an allylgroup, an acryl group, a methacryl group, an optionally substitutedbicyclo[2.2.1] heptene group, an optionally substitutedbicyclo[2.2.2]octene group, or an optionally substitutedoxabicyclo[2.2.1]heptene group, and wherein the compound which carries asulf(on)ate group and can attack the C═C double bond is a thioalkanesulfonate or an aminoalkane sulfonate.
 36. A method for preparing asilicic acid (hetero) polycondensate according to claim 17, comprisingthe steps of: generating or providing a silicic acid polycondensate fromat least two different silanes, including a silane with a first residuebonded by a carbon atom to silicon and carrying at least one organicallypolymerizable C═C double bond, with the proviso that no silanes in whichthe C═C double bonds are formed exclusively by methylene acrylic estersare generated or provided, and further including a silane with areactive residue bonded by a carbon atom to silicon and carrying areactive group; and reacting said reactive group of said silane withsaid reactive residue with a compound, said compound containing asulf(on)ate group and further containing a residue which can attack saidreactive group and form a link, so that the sulf(on)ate group isintroduced into said reactive residue.
 37. The method according to claim36, wherein said reactive group is a strained hetero ring.
 38. Themethod according to claim 37, wherein the strained hetero ring is anepoxy group.
 39. The method according to claim 37, wherein said compoundis sodium sulfate, sodium sulfite, a primary aminoalkane sulf(on)ate, ora secondary aminoalkane sulf(on)ate.
 40. The method according to claim36, wherein said compound is sodium sulfate, sodium sulfite, a primaryaminoalkane sulf(on)ate, or a secondary aminoalkane sulf(on)ate.